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MLD snooping configuration
This chapter includes these sections:
•
•
MLD snooping configuration task list
•
Displaying and maintaining MLD snooping
•
MLD snooping configuration examples
•
MLD snooping overview
Multicast Listener Discovery (MLD) snooping is an IPv6 multicast constraining mechanism that runs
on Layer 2 switches to manage and control IPv6 multicast groups.
Introduction to MLD snooping
By analyzing received MLD messages, a Layer 2 switch that is running MLD snooping establishes
mappings between ports and multicast MAC addresses and forwards IPv6 multicast data based on
these mappings.
As shown in
, when MLD snooping is not running, IPv6 multicast packets are broadcast to
all devices at Layer 2. When MLD snooping runs, multicast packets for known IPv6 multicast groups
are multicast to the receivers at Layer 2.
Figure 20 Before and after MLD snooping is enabled on the Layer 2 switch
MLD snooping forwards multicast data to only the receivers that require it at Layer 2. It brings the
following advantages:
•
Reducing Layer 2 broadcast packets, thus saving network bandwidth.
•
Enhancing the security of multicast traffic.
IPv6 multicast packet transmission
without MLD Snooping
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
IPv6 multicast packets
Layer 2 switch
IPv6 multicast packet transmission
when MLD Snooping runs
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
Layer 2 switch